How To Convert A Screwdriver To Lithium

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Conversion of a screwdriver to lithium batteries 18650

Every craftsman faces the problem of reduced tool performance, or complete failure due to the battery. Manufacturers use nickel-cadmium batteries in 12-volt, 14-volt, 18-volt screwdrivers. The sequential assembly of several elements creates the required voltage. Replacing nickel-cadmium batteries with lithium batteries extends battery life by making the design lighter. Mandatory BMS board installation adds reliability. Therefore, the conversion of a screwdriver to lithium batteries, mainly to the 18650 form factor, is justified.

Conversion of a screwdriver to lithium batteries 18650 14 V

When converting screwdrivers of different power and flashlights from Ni-Cd to Li-ion, batteries of the form factor 18650 are more often used. They easily fit into a container or a nest, since instead of two or three relatives, one lithium is installed. Alteration of the screwdriver battery should be carried out taking into account the characteristics of lithium 18650 batteries.

This type of energy source does not tolerate deep discharge and excessive charge. Hence, it is necessary to use voltage control boards. Since each battery has its own character, their charge is adjusted by a balancer. The point of reworking a screwdriver with a voltage of 14.4 V lies in creating a device using lithium batteries to facilitate a hand tool and increase its performance. Lithium 18650 batteries are most suitable for these purposes.

When selecting accessories, it should be taken into account that the starting current of the screwdriver is high, you must select the appropriate BMS for the required number of cans and at least 30 A.

  • Lithium-ion cans in the amount of 4 pcs.
  • 4 cell li-ion battery controller, CF-4S30A-A works well. It has a built-in balancer that controls the charge of each element.
  • Hot melt glue, flux for soldering TAGS, solder.
  • Heat-resistant adhesive tape;
  • Connecting jumpers or thick insulated wire with a cross section of at least 0.75 squares, cut for bridges.

The procedure for converting a screwdriver for 18650:

  • Disassemble the case and remove a bundle of 12 Ni-Cd cells from the container.
  • Remove the garland, leaving the connector with the “” and “-” pins. Instead of a temperature sensor, a thermocouple from the controller will be installed.
  • Solder the assembly, considering that you cannot use acid, only neutral flux and pure solder. During the connection period, do not warm up the lids. Work pointwise.
  • Connect balancing points to the controller according to the diagram. The board has connectors.
  • Connect assembly with plus and minus pins.
  • Check the functionality of the circuit. If everything works, assembled the battery, place the controller in the socket, secure with a sealant.

If the charger is not universal, additional alteration will be required. Screwdrivers for 12 V with a universal charger are assembled in the same way, but a protective connection circuit 3×18650 3.7 V for lithium batteries is used. In the same way, a screwdriver is reworked using a set of 18650 batteries in the amount of 2 elements.

Alteration of the “Hitachi” 12 V screwdriver for lithium batteries 18640

Peculiarities of reworking the 12 V Hitachi screwdriver for lithium batteries. The very compact battery compartment is designed for finger cells. Therefore, you should prepare a place for 18650 cells. It is necessary to cut one side of the partition to fit 1 element tightly.

You need to get a gumboil, a flat metal connecting tape, hot glue. It is necessary to install lithium batteries in a screwdriver during rework through a protective controller. It should serve 3 18650 cells, 3.7V, and rated for 20-30 amps.

Remove the old battery from the socket, carefully disconnect the contacts in the assembly with the temperature sensor and the power indicator. Clean up and sign contacts. They should be brought out in one direction, connected with solder to the leads from thick wires and filled with hot melt glue on the assembly.

Assemble a power source with one of the 3 cell controllers. Build a serial circuit of 3 Li-ion cells. Connect the controller. The conversion of the 12-volt lithium battery is completed when the structure is installed in the unit, secured, and the charging indicator lights up. After fully charging, the measurements show 12.17 volts in the external network. But this is enough for trouble-free long-term operation of the device.

Conversion of the Makita screwdriver to the lithium battery

There is a “Makita” screwdriver with a 1.3 A / h battery and a voltage of 9.6 V. To change the power source to a lithium-ion one, you will need 3 18650 components. The alteration will provide the old tool with new possibilities: it will increase the operating time on a single charge. will add power as the operating voltage rises to 10.8V.

The design will require the use of a BMS, a control controller that maintains the lithium cell operating mode within operating limits. With this breaker, each cell will be charged evenly without exceeding 4.2V, the lower voltage is 2.7V. The built-in balancer is used here.

The parameters of the controller should accompany the operation of the instrument when the operating current rises to 10-20 A. The Sony VTC4 30 A board, designed for a capacity of 2100 A / h, can ensure operation without shutdown. Of the 20 amps, the Sanyo UR18650NSX accepting 2600A / h energies is suitable. The board is needed for 3 elements, which is marked in the 3S classification. In this case, the board must have 2 contacts, plus and minus. If the conclusions are designated with the letters “P-“, “P”, “C-“, they are intended for later models of screwdrivers.

Step-by-step instructions for converting a Makita screwdriver to lithium batteries looks like this.

  • You can disassemble the battery with glue if you tap the junction with a soft-headed hammer while weighing. Direction of impact downward, butt-joint along the lower part of the body.
  • Take only contact plates from the old assembly, carefully disconnecting them from the battery. The sensor and the breaker must be left.
  • Solder 3 elements in series using TAGS flux and insulated jumpers. The wire cross-section must be greater than 0.75 mm2.
  • Assemble the circuit with the controller, and connect the power supply to the contact connectors with 1.5 square wires.
  • Check the functionality of the circuit and reassemble the case by placing it on glue again.

In a screwdriver with an old DC9710 charger, after charging the 18650 lithium battery, the red LED on the panel will turn off. The built-in controller monitors the charge level.

The Makita DC1414 T charger is used to charge 7.2-14.4 V power sources. While charging, the red light is on. But when charging a lithium battery, its voltage does not fit into the standards of salt products, and after 12 V, the charger will flash red and green. But the necessary charging is already there. The screwdriver is ready to work.

The meaning and procedure for converting screwdrivers to lithium batteries

Why do nickel-cadmium batteries fail quickly? In a garland of series-connected cans, each one is special. The chemical process is individual, the charge in closed systems is different. In the event of a malfunction in one bank, the design does not provide the required voltage. The control system and charge balancing are not provided in individual components.

  • Each Ni-Cd bank provides 1.2V and the li-ion 18650 provides 3.6V.
  • Lithium battery capacity is 2 times that of nickel-cadmium battery, similar size.
  • An overheated li-ion battery threatens an explosion and fire, therefore, the installation of control of the uniformity of the charge in the banks is mandatory. BMS is not installed in nickel-cadmium batteries. the manufacturer is not interested.
  • Lithium cells have no memory effect, unlike Ni-Cd, they can be charged at any time and within an hour.
  • The screwdriver becomes much easier after converting the battery to li-ion, using 18650 cells.
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There are only two obstacles to converting a screwdriver for lithium batteries. it is impossible to work with it at minus. The capacity of cans decreases, starting from a decrease already from 10 0 C. Lithium batteries are expensive.

Knowing what input voltage is required for the screwdriver, the charger is reworked, taking into account the placement of the lithium battery cells and control elements in the factory container. You can also do with a flashlight by upgrading the socket for a block of 18650 cells.

Let’s say you need to rework a 12 V screwdriver using Ni-Cd cans on li-ion. If you use 3 cans, the output voltage is not enough: 3.6 x 3 = 10.8 V. With 4 components, the power of the apparatus will be higher: 3.6 x 4 = 14.4 V. This will make the instrument 182 g lighter. its power will slightly increase, capacity. solid pluses. But when dismantling, you must leave the terminals and the native thermal sensor.

Alteration of the Interskol screwdriver for lithium batteries 18650

Sooner or later, the nickel-cadmium assembly of 15 cans fails. One or two elements are lazy, and it is no longer possible to get the output voltage. Modern DSh “Interskol” on lithium batteries serve much better. Alteration of a screwdriver for 18 volt lithium batteries mastered by craftsmen.

It is necessary to purchase a protection board for 5S, 3.7 V and 40-50 A. You will need a balancing board and the energy sources themselves. 5 lithium 18650 batteries, you can leave them with factory thermistors by extending the wires. During installation, create a contact pad, insert the assembly, check the operability, secure. The assembly features of the wizard’s advice are given in detail in the video. See here for full details on reworking an 18-volt lithium screwdriver

Method number 2 (reconstruction based on a network unit from a computer)

For this type of reconstruction, only an AT class network unit is suitable. Such devices have a ventilation compartment, as well as buttons on. and off. The network block is used on many computer models, so it will not be difficult for anyone to find an unnecessary part. Then check the output current, it should be at least 16 volts, and the power is 300.30 W.

  • Disassemble the device and find the plate on which the wiring is fixed (board).
  • Disable protection: locate the green electronic component on the board and attach to any other black wire.
  • Find a design with two black, yellow and red wires (MOLEX contacts). Attach or solder the extension cord to the yellow and black wires, and attach the other part to the screwdriver terminals. Now twist the mechanism.

Choosing a power supply for a screwdriver

The task can be accomplished in several details. For example, with a laptop charger, this rework is considered simple and unassuming. Therefore, if an unnecessary network block from a laptop is left at home, you can use it. Second detail. network block from a computer. This option implies a certain amount of knowledge and skills to work with a soldering iron. Another option is how to convert a screwdriver to a network one. engage the desired inverter welding. In the next section, we will tell you in detail how to implement your plan in all three ways.

Tip: Pay attention to the device parameters. For efficient drilling, the rpm must be at least 1300. For example, Bosch GSR 1440-LI and Makita DF347DWE machines have this characteristic.

Screwdriver alteration process

How to convert a cordless screwdriver to a network: 3 basic methods

It is not surprising that almost every house or apartment has a screwdriver. Unfortunately, devices based on a wireless network source often run out of power and break down. Since it is expensive to buy a new battery, most owners convert their cordless screwdrivers to cordless ones. In the article, we will tell you how to remake the device using the parts at hand. We will also touch on the topic of why this type of equipment breaks down most often. Read carefully!

reconstruction based on laptop power supply

As already mentioned, this reconstruction method is considered simple and does not require much time. Check first what output voltage the device is designed for. The best option would be 12-19 watts. In the next step, remove the unusable batteries from the device with a screwdriver and disassemble the device.

  • Disconnect the entry (sized for the laptop connector) and strip the wires.
  • Take the contacts and simply solder them to the device.
  • Select a location on the device for the wire and drill it. At the end of the action, fold the structure and check for operability.

Why convert a cordless screwdriver to a network?

Battery-charged equipment periodically discharges if not used for a long time. This fact is a problem, since the main components deteriorate when the charge in the battery drops frequently. As a result, during the first signs of breakdown, the battery holds less and less charge. In such a situation, complete breakdown of the part cannot be prevented, it is better to either replace it or change it to a new one. By the way, the cost of the first and second options will be the same.

Tip: If the user is going to work with hard surfaces, choose devices with rotation parameters of at least 20 Nm. This is the Sparky BR2 10.8Li-C HD mechanism.

The second reason is to remake the device. quality of work. Owners of such devices will easily confirm that the torque process is sometimes interrupted. It is also annoying that the power is not the best level. again, partial discharge is to blame. The situation is saved by connecting the device to the mains supply. Here are the benefits we get in the end:

  • Charging time will be reduced and you can start working at any time.
  • Functioning without limits, confidence that the device does not sit down halfway to the job done.
  • Financial benefit: no need to periodically change the battery.

Tip: On high-quality equipment, there is protection against breakages, which is located near the nozzle. Such protection is available for devices Bosch PSR 1200, Bosch GSR 12V-15.

(reconstruction based on inverter welding)

Reconstruction of a screwdriver when using inverter welding involves lengthy checks and calculations for the fact that the necessary parts are working. The process of reworking itself is not complicated, it adheres to the same technology as in the previous methods. You just need to remove the old battery, and in its place, attach the cord entry to the contacts. In the case of inverter welding, you will also need to install a secondary coil.

Based on the article read, we can say that this goal can be achieved in different ways. For this, a number of items are used, such as: laptop charger, computer power supply and inverter welding. However, the most successful and uncomplicated reconstruction will be based on a laptop power supply. So, not a huge detail will not weigh down the apparatus and will work for a long time. Be careful, all actions related to electrical devices oblige you to follow safety rules.

See Converting a cordless screwdriver to a mains

The meaning and procedure for converting screwdrivers to lithium batteries

Why do nickel-cadmium batteries fail quickly? In a garland of series-connected cans, each one is special. The chemical process is individual, the charge in closed systems is different. In the event of a malfunction in one bank, the design does not provide the required voltage. The control system and charge balancing are not provided in individual components.

convert, screwdriver, lithium
  • Each Ni-Cd bank provides 1.2V and the li-ion 18650 provides 3.6V.
  • Lithium battery capacity is 2 times that of nickel-cadmium battery, similar size.
  • An overheated li-ion battery threatens an explosion and fire, therefore, the installation of control of the uniformity of the charge in the banks is mandatory. BMS is not installed in nickel-cadmium batteries. the manufacturer is not interested.
  • Lithium cells have no memory effect, unlike Ni-Cd, they can be charged at any time and within an hour.
  • The screwdriver becomes much easier after converting the battery to li-ion, using 18650 cells.

There are only two obstacles to converting a screwdriver for lithium batteries. it is impossible to work with it at minus. The capacity of cans decreases, starting from a decrease already from 10 0 C. Lithium batteries are expensive.

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Knowing what input voltage is required for the screwdriver, the charger is reworked, taking into account the placement of the lithium battery cells and control elements in the factory container. You can also do with a flashlight by upgrading the socket for a block of 18650 cells.

Let’s say you need to rework a 12 V screwdriver using Ni-Cd cans on li-ion. If you use 3 cans, the output voltage is not enough: 3.6 x 3 = 10.8 V. With 4 components, the power of the apparatus will be higher: 3.6 x 4 = 14.4 V. This will make the instrument 182 g lighter. its power will slightly increase, capacity. solid pluses. But when dismantling, you must leave the terminals and the native thermal sensor.

Putting together a lithium-ion battery

Here are the new elements of Sanyo UR18650NSX (according to this article they can be found on Aliexpress) with a capacity of 2600 mAh. For comparison, the old battery had a capacity of only 1300 mAh, half the size.

It is necessary to solder the wires to the elements. The wires must be taken with a cross section of at least 0.75 sq. Mm, because we will have considerable currents. A wire with such a cross section normally works with currents of more than 20 A at a voltage of 12 V. You can solder lithium-ion cans, short-term overheating will not harm them in any way, this has been verified. But you need a good fast-acting flux. I use TAGS glycerin flux. Half a second. and you’re done.

We solder the other ends of the wires to the board according to the diagram.

I always put even thicker wires of 1.5 mm2 on the battery contacts. because the space allows. Before soldering them to the mating contacts, I put a piece of heat-shrink tubing on the board. It is necessary for additional isolation of the board from battery cells. Otherwise, the sharp edges of the solder can easily rub or puncture the thin film of the lithium-ion cell and cause a short. It is possible not to use heat shrinkage, but at least something insulating to be laid between the board and the elements is absolutely necessary.

Now everything is insulated as it should.

The contact part can be fixed in the battery case with a couple of droplets of super glue.

The battery is ready for assembly.

It’s good when the case is on the screws, but this is not my case, so I just glue the halves again “Moment”.

The battery is charged with a standard charger. True, the algorithm of work is changing.

I have two chargers, DC9710 and DC1414 T. And they work differently now, so I’ll tell you exactly how.

Conversion of the Makita screwdriver to the lithium battery

There is a “Makita” screwdriver with a 1.3 A / h battery and a voltage of 9.6 V. To change the power source to a lithium-ion one, you will need 3 18650 components. The alteration will provide the old tool with new possibilities: it will increase the operating time on a single charge. will add power as the operating voltage rises to 10.8V.

The design will require the use of a BMS, a control controller that maintains the lithium cell operating mode within operating limits. With this breaker, each cell will be charged evenly without exceeding 4.2V, the lower voltage is 2.7V. The built-in balancer is used here.

The parameters of the controller should accompany the operation of the instrument when the operating current rises to 10-20 A. The Sony VTC4 30 A board, designed for a capacity of 2100 A / h, can ensure operation without shutdown. Of the 20 amps, the Sanyo UR18650NSX accepting 2600A / h energies is suitable. The board is needed for 3 elements, which is marked in the 3S classification. In this case, the board must have 2 contacts, plus and minus. If the conclusions are designated with the letters “P-“, “P”, “C-“, they are intended for later models of screwdrivers.

Step-by-step instructions for converting a Makita screwdriver to lithium batteries looks like this.

Переделка шуруповёрта на литий Conversion of the screwdriver to lithium

  • You can disassemble the battery with glue if you tap the junction with a soft-headed hammer while weighing. Direction of impact downward, butt-joint along the lower part of the body.
  • Take only contact plates from the old assembly, carefully disconnecting them from the battery. The sensor and the breaker must be left.
  • Solder 3 elements in series using TAGS flux and insulated jumpers. The wire cross-section must be greater than 0.75 mm2.
  • Assemble the circuit with the controller, and connect the power supply to the contact connectors with 1.5 square wires.
  • Check the functionality of the circuit and reassemble the case by placing it on glue again.

In a screwdriver with an old DC9710 charger, after charging the 18650 lithium battery, the red LED on the panel will turn off. The built-in controller monitors the charge level.

The Makita DC1414 T charger is used to charge 7.2-14.4 V power sources. While charging, the red light is on. But when charging a lithium battery, its voltage does not fit into the standards of salt products, and after 12 V, the charger will flash red and green. But the necessary charging is already there. The screwdriver is ready to work.

How to convert batteries on a screwdriver to lithium

I won’t say anything new in this article, but I just want to share the experience of upgrading the batteries of my old Makita screwdriver. Initially, this tool was designed for nickel-cadmium batteries (which have long since died, just as those bought for replacement have died). The disadvantages of Ni-Cd are well known: low capacity, short lifespan, high price. Therefore, cordless tool manufacturers have long since switched to lithium-ion batteries.

Well, what about those who have an old instrument? Everything is very simple: throw away the Ni-Cd cans and replace them with Li-Ion of the popular 18650 format (the marking indicates the diameter is 18 mm and the length is 65 mm).

Preparatory moments

The first step is to determine the maximum voltage value. For this purpose, you need to calculate the number of elements. For three parts, the most acceptable value is 12 volts, for 4 parts. 16 volts.

Take as a basis a battery for a screwdriver with a maximum voltage of 14.4 V. In this case, it is recommended to use 4 cells. Thus, not only will the difference in volts be equalized, but the capacity indicator will also increase. It turns out that screwdrivers on a lithium battery can work much longer.

As for the type of batteries, experts recommend giving preference to the 18650 series, it is the most optimal option. Next, you need to deal with the capacity and discharge current. With the normalized operation of the device, the consumed current level varies within 5-10 Am. But if an unexpected sharp descent occurs, then the value rises to 25 Am. In order not to harm the battery during such a drop, it is recommended to select cells with an increased value of the discharge current, for example, up to 30 Am.

High discharge current 18650 batteries

Instead of four lithium ion cans, eight can be used. But for this it is necessary to fasten 2 elements in parallel. Further, the connecting pairs must be connected in series. It is important to consider here that not all battery cases are capable of accommodating 8 parts at the same time.

The controller must be selected according to the indicator of the rated voltage, as well as taking into account the discharge current. These values ​​must match. precisely, the voltage will completely coincide for both the battery and the controller, but only the operating discharge current should be 2 times less than the limit.

For example, it looks like this. the controlling device for charging-discharging is calculated for 13-14 Am, while the protective function will turn on when the current rises sharply to 30 Am.

Even when converting a screwdriver to lithium, it is necessary to take into account the dimensions of the protective board, since it must completely fit into the equipment case. Otherwise, it is necessary to use imagination to increase the body part. Leaving this part open is strongly discouraged.

Change Old Dead BOSCH Battery/ NI-MH Ni-Cd To Li ion With Test

Pros and cons of modernization

Before converting a screwdriver to lithium 18650 batteries, you need to figure out what the master will get as a result. The advantages of these manipulations are as follows:

  • multiple increase in the operating time of the screwdriver;
  • increasing the battery charge rate. for a full-fledged set of energy for lithium batteries, approximately 1 hour is needed;
  • an increase in the charge current power to an indicator of 1-2 C;
  • reducing the cost of regularly purchasing new NiCd batteries due to their insufficient operating life;
  • complete absence of memory effect in lithium batteries.
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Also, before remaking a battery with your own hands for a more modern technology, you should be aware of the negative consequences:

  • a mandatory connection of the controller is required to determine the charge level, since the device cannot be charged more than 4.2 V and discharged less than 2.7 V;
  • lithium-ion batteries for the Li-lon series screwdrivers lose their ability when operated in low temperature conditions;
  • when converting a screwdriver to a lithium battery, it may be difficult to adapt the charger from NiCd, here you will have to use a universal device.

How to disassemble a screwdriver battery

How to disassemble an old battery? There are batteries where the halves of the case are fastened with screws, but there are also glue ones. My batteries are just the latest ones, and for a long time I generally believed that they could not be disassembled. It turned out that it is possible if you have a hammer.

In general, with the help of intense blows to the perimeter of the edge of the lower part of the case (a hammer with a nylon head, the battery must be held in the hand by weight), the gluing site is successfully disconnected. At the same time, the case is not damaged in any way, I have already disassembled 4 pieces this way.

The part of interest to us.

From the old circuit, only contact plates are needed. They are permanently spot welded to the upper two elements. You can pick out the welding with a screwdriver or pliers, but you need to pick it as carefully as possible so as not to break the plastic.

Everything is almost ready for further work. By the way, I left the standard thermal sensor and disconnector, although they are no longer particularly relevant.

But it is very likely that the presence of these elements is necessary for the normal operation of a standard charger. Therefore, I highly recommend saving them.

Converting a screwdriver battery to lithium cells

Many screwdriver owners want to convert their batteries to lithium battery cells. Many articles have been written on this topic and in this material I would like to summarize information on this issue. First of all, we will consider the arguments in favor of converting a screwdriver to lithium batteries and against it. And also consider some moments of the process of replacing batteries.

All pros and cons of converting a screwdriver battery to lithium cells

First, you should think about whether I need this alteration? After all, it will be an outright “self-propeller” and in some cases can lead to failure of both the battery and the screwdriver itself. Therefore, let’s consider all the pros and cons of this procedure. It is possible that after that some of you will decide to abandon the conversion of the Ni─Cd battery for a screwdriver to lithium cells.

Replacing batteries in a screwdriver with lithium

The pros

Let’s start with the benefits:

  • The energy density of lithium-ion cells is much higher than that of nickel-cadmium, which are used by default in screwdrivers. That is, the battery on lithium cans will have less weight than on cadmium with the same capacity and output voltage;
  • Lithium battery cells are charged significantly faster than Ni-Cd. It will take about an hour to charge them safely;
  • Lithium ion batteries have no memory effect. This means that they do not need to be fully discharged before charging.

Now about the disadvantages and complexities of lithium batteries.

The cons

  • Lithium battery cells cannot be charged above 4.2 volts and discharged below 2.7 volts. In real conditions, this interval is even narrower. If you go beyond these limits, the battery can be damaged. Therefore, in addition to the lithium cans themselves, you will need to connect and install a charge-discharge controller in the screwdriver;
  • The voltage of one Li─Ion cell is 3.6─3.7 volts, and for Ni─Cd and Ni─MH this value is 1.2 volts. That is, there are problems with assembling a battery for screwdrivers with a voltage rating of 12 volts. From three lithium cans connected in series, you can assemble a battery with a nominal value of 11.1 volts. Out of four ─ 14.8, out of five ─ 18.5 volts, and so on. Naturally, the voltage limits during charge-discharge will also be different. That is, there may be problems with the compatibility of the converted battery with a screwdriver;
  • In most cases, 18650 cans are used in the role of lithium cells for alteration. They differ in size from Ni─Cd and Ni─MH cans. In addition, you will need space for the charge-discharge controller and wires. All this will need to fit in a standard battery case of a screwdriver. Otherwise, it will be extremely inconvenient for them to work;
  • A cadmium battery charger may not be suitable for recharging a battery after a redesign. You may need to revise the charger or use universal chargers;
  • Lithium batteries lose their performance at low temperatures. This is critical for those who use a screwdriver outdoors;
  • The price of lithium batteries is higher than cadmium.

What you need to estimate before starting work?

It is necessary to determine the number of cells in the battery, which ultimately decides the voltage value. For three elements, the ceiling will be 12.6, and for four. 16.8 volts. We are talking about reworking widespread batteries with a nominal value of 14.4 volts. It is better to choose 4 elements, since during operation the voltage will drop pretty quickly to 14.8. A difference of a few volts will not affect the operation of the screwdriver.

In addition, more lithium cells will give more capacity. This means longer operating time of the screwdriver.

Lithium battery cells 18650

The nominal voltage of lithium cells is 3.6-3.7 volts, and the capacity in most cases is 2000-3000 mAh. If the battery case allows, you can take not 4, but 8 cells. Connect them two by two into 4 parallel assemblies, and then connect them in series. As a result, you will be able to increase the battery capacity. But not every case will be able to pack 8 cans of 18650.

And the last preparatory step is choosing a controller. According to its characteristics, it must correspond to the rated voltage and discharge current. That is, if you decide to assemble a 14.4 volt battery, then choose a controller with this voltage. The working discharge current is usually chosen half of the maximum permissible current.

Charge-Discharge Controller Board

Above, we established that the maximum permissible short-term discharge current for lithium cells is 25-30 amperes. This means that the charge-discharge controller must be rated for 12-15 amperes. Then the protection will be triggered when the current increases to 25-30 amperes. Do not forget also about the dimensions of the protection board. It, together with the elements, will need to fit into the battery case of the screwdriver.

Battery replacement

Well, then the assembly process itself goes. Disassemble the battery case first. If this is a 14.4 volt model, then there will be 12 nickel cadmium batteries with a nominal value of 1.2 volts inside.

Assembling Nickel Cadmium Batteries

After that, you need to solder the purchased items into an assembly with a serial connection. Next, the controller is soldered to it in accordance with its circuit. In this case, balancing points are connected. The board has a special connector for them, and often wires with a connector are supplied in the kit.

Screwdriver battery housing

After assembling the battery, the terminals for plus and minus are soldered, and the whole structure is placed in the case. In principle, the process is over. Problems can only arise with the charger. But in most cases, standard chargers for screwdrivers charge lithium cells without problems. In this case, the charge of the cans goes through the controller, so nothing terrible will happen to the elements themselves.